class_docstr: Template meson build file generation class.
code: def sources_substitution(self) -> None:
      indent = " " * 21
      self.substitutions["source_list"] = f",\n{indent}".join(
          [f"{indent}'{source}'" for source in self.sources]
      )
  
imports: from __future__ import annotations
  import os
  import errno
  import shutil
  import subprocess
  import sys
  from pathlib import Path
  from ._backend import Backend
  from string import Template
  from itertools import chain
  import warnings
label_desc: Use image node_id 4 for calling the MesonTemplate obj's underlying member method code with example usage: obj.sources_substitution() without return types